Circuit breaker



May 15, 1928. 1,6?0,121' E.D.MOORE CIRCUIT BREAKER Filed July 23, 1924 2Sheets-Sheet 1 May 15, 1928.

R 1,670,121 E. D. MOORE CIRCUIT BREAKER Filed July 23, 1924 2Sheets-Sheet 2 MMMM Patented May 15,- 1928.

EDGAR D. MOORE, OI CLEVELAND, OHIO.

CIRCUIT BREAKER.

Application fled July 28, 1924. Serial No. 727,882.

This invention relates to circuit opening devices and has particularreference to a safety switch or circuit breaker embodying certalnimprovements over those disclosed in my copending applications SerialNos. 637,176 and 662,663, filed May 7, 1923 and Sept. 14, 1923, resectively,.the latter now being Patent Num r 1,643,415, dated September27, 1927.

Motors and similar devices are designed to operate atvarious overloadswith corresponding time periods without damage. W'hen protected by therated fuse, the fuse will permit the momentary current surge presentwhen starting the motor, but will not permit the motor to operate at anoverload over an appreciable time which could be done without damage tothe motor and is sometimes desirable.

As a specific example of the above statements, it might be pointed outthat a washing machine using an electric motor as a source of power tooperate the washing mechanism and wringer, when protected by a suitablefuse of say 10 amperes, will operate satisfactorily as long as thewashing mechanism and wringer are'not overloaded. If however, thewashing mechanism is being operated and the Wringer is operated at aslight overload, the fuse will blow and a new fuse will have to besubstituted. If

-the machine is protected only by the house fuse of much larger capacityof say 25 amperes which is the usual case, the machine may operate atoverloads without blowing the fuse but there is danger in this instanceof operating the motor at an overload over too long a period of time sothat the motor will be damaged. It is thus apparent that a motor drivendevice of this character is not protected at all, or is so protectedthat slight overloads which are not apt to be dan erous will cause therepeated blowing of fiises during the operation of the machine.

It is the general object of the present invention to provide a circuitbreaker which shall protect the device in circuit therewith in threedistinct ways so that it shall be impossible for the device to besubjected to sudden and dangerous high current surges; an overloadcurrent for a greater period of time than the rated time; or repeatedcurrent surges due to resetting of the circuit breaker before the sourceof trouble has been remedied.

Another object is breaker of the aforesaid character which shall bepositive in action and which shall break the circuit with a snap actionto prevent arcin A still urther object is to provide a circuit breakerwhich shall be simple in construction, inexpensive to manufacture andwhich shall be reliable in operation.

With these and other objects in view, the invention consists in thevarious novel features of construction and arrangement or combination,all of which will be fully described hereinafter and pointed out in theappended claims.

In the accompanying drawings, Fig. 1 is a side elevation of a circuitbreaker constructed in accordance with my invention and showing the samein closed circuit position; Fig. 2 is a similar view but showing thecircuit breaker in open position; Figs. 3 and tare transverse sectionalviews taken respectively on the lines 33 and 44 of Fig. 1; Fig. 5 is aside elevation of the circuit breaker showing the main contacts inclosed position and the auxiliary contacts in open circuit position;Fig. 6 is an'end elevation showing a plurality of circuit breakersmounted in gang formation; and Fig. 7 is a diagrammatic viewillustrating the electrical circuit.

Describing the various parts by reference characters, 1 denotes thehousing for my device which may be in the form of a rectangular metallicbox open on one side when the devices are to be assembled in bankformation as will be explained hereinafter, or closed entirely on allsides and ends when used individually. Secured within the housing is ashelf 2 and arranged between this shelf and one end of the housing is asolenoid consistin of a non-magnetic sleeve 3 about which 1s disposed awinding 4. A

plunger 5, having a longitudinal bore 6 therein, is slidably mountedwithin sleeve 3.

Fastened to the opposite side of shelf 2 is an insulating strip 8 whichhas fastened thereto a pair of contact springs 9 and 10 which arearranged in spaced relation. Adjacent the end of each contact springthere is fastened a bifurcated arm 11 each of which pivotally receivesone end of a link 12 formed from insulating material. The inner ends ofthese links are recessed as indicated at'13 (Fig. 3) and are arranged inoverlapping relatio A bifurcated arm 14 is pivto provide a circuit tionin arm 14 and a cushioning washer 19 4 is positioned on top of the locknut.

1 i the auxiliary contacts.

In this connection it Will be pointed out that screw 16 is slidablymounted in the end of solenoid plunger 5 for a purpose to be referred tomore particularly hereinafter.

A metal plate 20 having an insulating section 21 inset therein, isslidably mounted on screws 22 which depend from insulating strip 8. Thisplate is normally urged toward strip 8 by means of springs 23 which areinterposed between the heads of screws 22 and the plate. A pair ofspaced contacts 24' and 25 are fastened to strip 8, and plate 20 isadapted to contact therewith to complete the electrical circuittherebetween, the

insulating'section 21 being adapted to contact-with the end of solenoidplunger 5. Plate 20 and contacts 24 and 25 constitute Fastened toopposite sides of housing 1 and insulated therefrom by means ofinsulating blocks 25 are stationary contacts 26 and 27 which aredisposed in line with the contact springs 9 and 10, and these contactsand contact springs constitute the main contacts. Contact 26 extendsthrough the housing and is fitted with a thumb nut 28 to facilitateelectrical connection therewith.

Arranged within the housing 1 adjacent one end thereof is -an insulatingblock 39 to which is pivotally fastened an arm 31 asb means of a screw32. The outer end of t is arm has fastened thereto a thermostaticelement 33 which is provided adjacent its upper end with a projection 34having an'inclined edge 35 that is adapted to engage pivot pin 15. Aheating coil 36 is disposed about thermostatic element 33 and is adaptedto heat said element to cause it to warp so as to disengage projections34 from pin 15. In this connection it will be noted that arm 31.may berocked about screw 32 to any desired position and thereby vary thelength of time that projection 34 will engage pin 15. One end of heatingcoil 36 is connected to a bindin post 38 which is fastened to housing 1an insulated therefrom, and the other end of the heating coil isfastened to stationary contact 27 When the circuit breaker is insertedin series circuit with the electrical, device to be protected, currentwill flow from the line (Fig. 7 to binding post 38, through heating coil36, stationary contact 27, contactv spring 10, thence to auxiliarycontact 24, through plate 20 to auxiliary contact 25, then throughsolenoid winding 4 to contact spring 9 and stationary contact 26 to thedevice to be protected indicated generally at 40, and thence back to theline. It will be understood of course that current may flow in anopposite direction equally well and the above is merely selected as anexam le.

During the time that current is owing, heating coil 36 is heatingthermostatic element 33, however insuflicient heat will be generated towarp element 33 a distance. sufficient to disengage projection 34 frompin 15 so long as the current flow is normal. If the electrical deviceis operated at an overload, suflicient heat will be developed during .aperiod of )time, dependent uponthe extent of the overload, to

,warp element 33 and disengage pro'ection 34 from pin 15. The currentowing through the circuit and particularly through solenoid winding 4will cause solenoid plunger 5 to exert a pull through screw 16 to thearin 14 and links 12 thereby forcibly pulling contact springs 9 and 10away from their respective stationary contacts 26 and 27 and opening theelectrical circuit as shown in Fig.2. The thermostatic element ispreferably set by means of screw 32 so as to disengage pin 15 just ina'dvance of the time that the overload would injure the particularelectricaldevice which is to be protected.

If the operator attempts to reset the circuit breaker before theelectrical device has cooled and also before the thermostatic elementhas cooled, no harm will be done. I As the resetting handle 39 is pushedinwardly plunger 5 moves inwardly and engages plate 20 forcing it'awayfrom auxiliary contacts 24 and 25 thereby opening the circuit. Continuedinward movement will force the plate 20 into contact with washer 16 andhence force arm 14 inwardly which in turn forces the inner ends oftoggle arms 12 inwardly and thereby engages contact springs 9 and 10with their respective contacts 26 and 27. However projection 34 is outof alignment with pin 15 and hence when the handle 39 is released themain contacts will return to open circuit position and the auxiliarycontacts will return to closed circuit position. It will thus be obviousthat the auxiliary contacts will be maintained in open circuit positionuntil the main contacts are opened, hence no current will flow. If,however, the electrical device to be protected and hence thethermostatic element 33 have cooled sufficiently, then when theoperating handle 39 is pushed inwardly, the pin 15 will be engaged underthe projection 34 and the main contacts will remain closed and thecircuit will be completed as soon as plate 20 engages the auxiliarycontacts.

If there should be a sudden current surge throu h the circuit suflicientto damage the electrlcal device, the circuit breaker willbe tripped bythe increased ull on plunger 5.

pull the pin from beneath the inclined edge of projection 34 as thethermostatic element 33 1s of a resilient nature and would. be deflectedto one side. If the operator should attempt to reset the circuit breakerbefore the cause for the current surge has been removed, no harm will bedone as the auxiliary contacts are automatically opened during theresetting of the main contacts and when the plunger handle is releasedso as to cause the auxiliary contacts to close, the main contacts willbe tripped immediatelly Y due to the pull on solenoid plunger 5.

is thus impossible for the operator to hold the circuit breaker inclosed circuit position. From the foregoing description it will beobvious that I have provided a practically fool proof circuit breakerwhich oifers maximum protection to an electrical circuit in thefollowing ways: First. Protection against overloads extending over aperiod of time greater than the rated period of time for the particularelectrical device.

Second. Protection against resettin the circuit breaker before theelectrical (evice has cooled to its normal working temperature.

Third. Protection against sudden current surges due to short circuits oroverloads greater than the rated overload.

Fourth. Protection against resetting the circuit breaker before thecause of the current surge has been remedied.

Fifth. Protection against the operator forcibly holding the circuitbreaker in closed circuit osition.

The circuit breaker described may be used individually as for example ona washing machine or other electrical device, or a plurality of them maybe mounted in gang formation as shown in Fig. 6 and each control aseparate circuit. This latter type of installation being particularlyuseful for house lighting circuits and similar uses.

The circuit breaker provides a quick snap break at the main contacts andhence eliminates arcing at these points. The device is easily reset andrequires no special skill or care in use.

Having thus described my invention, what I claim is:

1. A circuit breaker ofthe character set forth comprisin a housinghaving a solenoid winding t erein, a plunger slidably mounted withinsaid winding, a set of main contacts and a set of auxiliary contacts incircuit with said main contacts, a connection between said main contactsand said plunger whereby a predetermined flow'of current through saidwinding will move said plunger to open said main contacts, means forcausing said auxiliary contacts to open during the resetting of saidmain contacts, and a thermal element adapted to be moved contacts toopen.

to permit said contacts to open upon an excessive flow of currentthrough said winding extending over a predetermined period of time.

2. A circuit breaker of the character set forth comprisin a housinghaving a solenoid winding t erein, a plunger slidably mounted withinsaid winding, a set of main contacts and a set of auxiliary contacts incircuit with said main contacts, a connection between said main contactsand said plunger whereby a predetermined flow of current through saidwinding will move said plunger to open said contacts, means normallyurging said auxiliary contacts to closed position, a connection betweensaid auxiliary contacts and said plunger whereby movement of saidplunger to close said main contacts will open said auxiliary contacts, athermal element normally holdin said main contacts in closed position,an a heating coil disposed in operative relation to said thermalelement, said coil being in circuit with said winding whereby apredetermined flow of current through said coil and winding will warpsaid thermal element and permit said main contacts to open.

3. A circuit breaker of the character set forth comprising a housinghaving a solenoid .winding therein, a plunger slidably mounted withinsaid winding, a set of main contacts and a set of auxiliary contacts incircuit with said main contacts, a connection between said main contactsand said plunger whereby a predetermined flow of current through saidwinding will move said plunger 'to open said contacts, means for openingsaid auxiliary contact during the resetting of said main contacts, athermal element adapted to engage the connection between said plungerand main contacts and normally retain said contacts in closed position,and a heating coil disposed in operative relation to said thermalelement, said coil being in circuit with said winding whereby apredetermined flow of current through said and winding will generatesufiicient heat in said coil to warp said thermal element to disengagesaid connection and permit said main 4. A circuit breaker of thecharacter set forth comprising a set of main contacts and a set ofauxiliary contacts in circuit with said main contacts, magnetic meansconnected to said main contacts and adapted to open the same upon acurrent flow in excess 0 a predetermined value, means connecting saidauxiliary contacts with said magnetic means whereby saidauxiliary'contacts are opened during the resetting of said maincontacts, a thermal element operatively" connected to said maincontacts, and means for hcatin said thermal element in proportion tosaid current flow, said thermal element being adapted to be moved topermit said main contacts to open at apredetermined current flowextending over a predetermined period of time. V

5. A circuit breaker of the character set forth comprising a set of maincontacts and a set of auxiliary contacts in circ it with said maincontacts, magnetic means connected to said main contacts and adapted toopen the same upon a current flow in ex- :ess of a predetermined value,means connecting said auxiliary contacts with said magnetic meanswhereby said auxiliary contacts are opened during the resetting of saidmain contacts, a. thermal element oper'atively connected with said maincontacts, and a resistance .element for heating said thermal element inproportion to said current flow, said thermal element being adapted towarp thereby to'permit said main contacts to open at a predeterminedcurrent flow extending over a predetermined period of time.

6. A circuit breaker of the character set.

forth comprisin a housing having a sole- :noid winding t erein, a,plunger slidably mounted within said winding, a set of main contacts anda set of auxiliary contacts in circuit with said main contacts, aconnection between said main contacts and said plunger whereby apredetermined flow of current through said winding will move said plunerto open said main contacts, means for causing said auxiliary contacts toautomatically open during the resetting of said main contacts, a thermalelement operatively connected to said main contacts in closed position,and means for heating said thermal element thereby to warp said elementto permit saidmain contacts to open upon an excessive flow of currentthrough said winding extending over a predetermined period oftime.

7. A circuit breaker of the character set forth comprising a housinghaving a solenoidwinding therein, an armature mounted in operativerelation to said winding, a set of main contacts and a set of auxiliarycontacts f r I 'in circuit with said main contacts, a connecclosedposition, a connection between said auxiliary contacts and said armaturewhereby movement of said armature to close said main contacts will opensaid auxiliary contacts, a thermal'element normally holding said maincontacts in closed position, and a heating coil disposed in operativerelation to said thermal element, said coil being in circuit with saidwinding whereby a prede- .termined flow of current through said coil andwinding will warp said thermal element and permit said main contacts toopen.

8. A circuit breaker of the character set forth comprising a housinghaving a solenoid winding therein, an armature mounted in operativerelation to said winding, a'iset of mam contacts and a set of auxiliarycontacts in circuit with said main contacts, a

connection between said main contacts and said armature whereby apredetermined flow of current through said winding will move saidarmature to open said main contacts,

means for opening said auxillary contacts during the resetting of saidmain-contacts, a thermal element adapted to engage. the connectionbetween said armature and main contacts and normally retain saidmaincontacts in closed position, and a heating coil disposed inoperative. relation to said thermal element, said coil being in circuitwith said winding whereby a predetermined flow of current through saidcoil and winding will generate spfiicient heat in said coil to warp saidthermal element to disengage said connection and permit said maincontacts to open.

in testimony whereof, I hereunto afix my signature.

mean n. MOORE.

